Independent maritime surveying knowledge platform. Practical, source-verified guidance on draft survey, bunker survey, cargo inspection, sampling and marine claims.https://surveyera.com/en-gb© 2026 SurveyErahttps://surveyera.com/cargo-survey/hatch-cover-weathertightness-checklist/https://surveyera.com/cargo-survey/hatch-cover-weathertightness-checklist/Before loading, hatch covers are inspected for the condition of the packing and its channel, correct compression, the condition of cross-joint seals and wedges, the state of the coaming and compression bar, and clear drain channels with working non-return valves. Most wet damage claims trace to compression and drainage rather than to a visibly torn seal.Mon, 14 Sep 2026 00:00:00 GMTCargo SurveySurveyor ChecklistSurveyEra Editorialhttps://surveyera.com/draft-survey/what-is-tpc/https://surveyera.com/draft-survey/what-is-tpc/TPC — tonnes per centimetre immersion — is the weight that must be added or removed to change a vessel's mean draft by one centimetre at a given draft. It comes from the waterplane area and the water density, and in a draft survey it converts a difference in draft into a difference in weight.Mon, 14 Sep 2026 00:00:00 GMTDraft SurveyKnowledge NoteSurveyEra Editorialhttps://surveyera.com/draft-survey/trim-correction-explained/https://surveyera.com/draft-survey/trim-correction-explained/Trim corrections adjust the displacement read from the hydrostatic tables for the fact that a trimmed vessel does not float at the draft the tables assume. The first correction allows for the LCF not being at amidships; the second allows for the change in waterplane shape as the vessel trims. Both are applied to displacement before any deductibles.Mon, 14 Sep 2026 00:00:00 GMTDraft SurveyExplainerSurveyEra Editorialhttps://surveyera.com/draft-survey/how-to-perform-a-draft-survey/https://surveyera.com/draft-survey/how-to-perform-a-draft-survey/A draft survey determines cargo quantity by measuring the vessel's displacement before and after cargo work. Six drafts are read and corrected to the perpendiculars, a quarter mean allows for hull deflection, displacement is taken from the hydrostatic tables and corrected for trim and water density, non-cargo weights are deducted, and the difference between the two net displacements is the cargo.Mon, 14 Sep 2026 00:00:00 GMTDraft SurveyTechnical GuideSurveyEra Editorial